Liquid discharge device, and liquid discharge unit

Abstract

To radiate heat generated in a first transistor with good efficiency.SOLUTION: A liquid discharge unit comprises: a drive element driven by a driving signal; a liquid discharge head which discharges a liquid according to driving of the drive element; and a driving signal generation unit which generates the driving signal. The driving signal generation unit comprises: an integrated circuit which outputs a first control signal and a second control signal; a first transistor to which the first control signal is inputted; a second transistor to which the second control signal is inputted; a coil electrically connected to an output terminal of which one end is electrically connected to the first transistor and the second transistor, and the other end is electrically connected to an output terminal which outputs the driving signal; a base plate on which the integrated circuit, the first transistor, the second transistor, and the coil are mounted; and a mold member which covers the first transistor on the base plate. The first transistor has a Cu clip structure.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection device and a liquid ejection unit. [Background technology]

[0002] A liquid ejection device is known that includes a liquid ejection unit that ejects a liquid such as ink in response to a drive signal, and a drive signal generation unit that generates the drive signal. For example, Patent Document 1 discloses a liquid ejection device that includes an integrated circuit that outputs a first control signal and a second control signal, a first transistor to which the first control signal is input, a second transistor to which the second control signal is input, a coil having one end electrically connected to the first transistor and the second transistor and the other end electrically connected to an output terminal that outputs the drive signal, and a substrate on which the integrated circuit, the first transistor, the second transistor, and the coil are mounted, and that is characterized in that heat generated in the first transistor is dissipated from the substrate via a plurality of electrodes provided on a first surface facing the substrate, among multiple surfaces of a chip body (also referred to as a "die") of the first transistor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-117049 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the drive signal for driving the liquid ejection unit is a large-amplitude signal, and the first transistor generates a large amount of heat when generating the drive signal. Therefore, when the heat generated in the first transistor is dissipated from the substrate via multiple electrodes provided on the first surface of the chip body of the first transistor, as in conventional technology, the amount of heat generated in the first transistor exceeds the amount of heat dissipated from the substrate, causing the temperature of the first transistor to rise. When the temperature of the first transistor rises, the operation of the drive signal generation unit can become unstable. [Means for solving the problem]

[0005] In order to solve the above problems, the liquid ejection device of the present invention comprises: a liquid ejection unit having a drive element driven by a drive signal and ejecting liquid in response to driving of the drive element; and a drive signal generation unit that generates the drive signal, wherein the drive signal generation unit comprises: an integrated circuit that outputs a first control signal and a second control signal; a first transistor to which the first control signal is input; a second transistor to which the second control signal is input; a coil having one end electrically connected to the first transistor and the second transistor and the other end electrically connected to an output terminal that outputs the drive signal; a substrate on which the integrated circuit, the first transistor, the second transistor, and the coil are mounted; and a molded member that covers the first transistor on the substrate, wherein the first transistor has a Cu clip structure.

[0006] Furthermore, the liquid ejection unit according to the present invention is a liquid ejection unit that includes a drive element that is driven by a drive signal and ejects liquid in response to the drive of the drive element, and includes an integrated circuit that outputs a first control signal and a second control signal, a first transistor to which the first control signal is input, a second transistor to which the second control signal is input, a coil having one end electrically connected to the first transistor and the second transistor and the other end electrically connected to an output terminal that outputs the drive signal, a substrate on which the integrated circuit, the first transistor, the second transistor, and the coil are mounted, and a molded member that covers the first transistor on the substrate, and the first transistor has a Cu clip structure. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a block diagram showing an example of the configuration of an inkjet printer 1 according to a first embodiment of the invention. [Figure 2] FIG. 1 is a perspective view showing an example of a schematic internal structure of an inkjet printer 1. [Figure 3] FIG. 10 is a cross-sectional view showing an example of the structure of a discharge section D[m]. [Figure 4] FIG. 2 is a block diagram showing an example of the configuration of a drive signal generating circuit 4. [Figure 5] 2 is a block diagram showing an example of the configuration of a liquid ejection unit 3. FIG. [Figure 6] 10 is a timing chart showing an example of a signal supplied to the liquid ejection unit 3. [Figure 7] FIG. 10 is an explanatory diagram showing an example of an individual designation signal Sd[m]. [Figure 8] FIG. 2 is a cross-sectional view showing an example of the structure of a drive signal generating unit 5. [Figure 9] FIG. 10 is a cross-sectional view showing an example of the structure of a drive signal generating unit 5W according to a conventional example. [Figure 10] 2 is an explanatory diagram showing an overview of a drive signal generation unit 5 and a drive signal generation unit 5W. FIG. [Figure 11]It is a cross-sectional view showing an example of the structure of a drive signal generation unit 5B according to the second embodiment of the present invention. [Figure 12] It is an explanatory view showing an example of the composition of the reaction solution. [Figure 13] It is a cross-sectional view showing an example of the structure of a drive signal generation unit 5C according to the third embodiment of the present invention. [Figure 14] It is a block diagram showing an example of the configuration of an inkjet printer 1D according to Modification 1 of the present invention. [Figure 15] It is a cross-sectional view showing an example of the structure of a drive signal generation unit 5B according to Modification 2 of the present invention. [Figure 16] It is a cross-sectional view showing an example of the structure of a drive signal generation unit 5C according to Modification 2 of the present invention.

Mode for Carrying Out the Invention

[0008] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. However, in each figure, the dimensions and scales of each part are appropriately different from the actual ones. In addition, the embodiments described below are preferred specific examples of the present invention, so various technically preferable limitations are imposed. However, the scope of the present invention is not limited to these embodiments unless there is a description specifically limiting the present invention in the following description.

[0009] <<A. First Embodiment>> In the first embodiment, an inkjet printer 1 that discharges ink to form an image on a recording paper PP is exemplified to explain a liquid discharge device.

[0010] <<A.1. Outline of Inkjet Printer>> Hereinafter, an example of the configuration of an inkjet printer 1 according to the first embodiment will be described while referring to FIGS. 1 to 3.

[0011] FIG. 1 is a functional block diagram showing an example of the configuration of an inkjet printer 1.

[0012] 1, print data Img indicating the image to be formed by the inkjet printer 1 is supplied from a host computer such as a personal computer or digital camera to the inkjet printer 1. The inkjet printer 1 executes a printing process to form the image indicated by the print data Img supplied from the host computer on recording paper PP.

[0013] As shown in Figure 1, the inkjet printer 1 includes a control unit 2 that controls each part of the inkjet printer 1, a liquid ejection unit 3 provided with an ejection section D that ejects ink onto recording paper PP, a drive signal generation unit 5 provided with a drive signal generation circuit 4 that generates a drive signal Com for driving the ejection section D, and a transport unit 9 that transports the liquid ejection unit 3 and recording paper PP. In the first embodiment, the inkjet printer 1 is an example of a "liquid ejection device," the ink is an example of a "liquid," and the recording paper PP is an example of a "medium."

[0014] In the first embodiment, it is assumed that the inkjet printer 1 includes one or more liquid ejection units 3 and one or more drive signal generation units 5 that correspond one-to-one to the one or more liquid ejection units 3. Specifically, in the first embodiment, it is assumed that the inkjet printer 1 includes four liquid ejection units 3 and four drive signal generation units 5 that correspond one-to-one to the four liquid ejection units 3. However, for ease of explanation, the following description may focus on one of the four liquid ejection units 3 and one of the four drive signal generation units 5 that is provided to correspond to one of the liquid ejection units 3, as shown in FIG.

[0015] The control unit 2 is configured to include one or more central processing units (CPUs). However, the control unit 2 may include a programmable logic device such as a field-programmable gate array (FPGA) instead of or in addition to a CPU. The control unit 2 also includes a memory. The memory is configured to include one or both of a volatile memory such as a random access memory (RAM) and a non-volatile memory such as a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), or a programmable ROM (PROM).

[0016] The control unit 2 generates signals for controlling the operation of each part of the inkjet printer 1, such as a specification signal SI, a waveform specification signal dCom, a carriage transport control signal SK, and a medium transport control signal SB.

[0017] Here, the waveform specification signal dCom is a digital signal that defines the waveform of the drive signal Com. The drive signal Com is an analog signal for driving the discharge section D. The specification signal SI is a digital signal that specifies the type of operation of the discharge section D. Specifically, the specification signal SI specifies whether or not to supply the drive signal Com to the discharge section D, thereby specifying the type of operation of the discharge section D, such as whether or not to discharge ink from the discharge section D. The carriage transport control signal SK and the medium transport control signal SB are signals for controlling the transport unit 9.

[0018] When a printing process is performed, the control unit 2 generates signals, such as a designation signal SI, for controlling the liquid ejection unit 3 based on the print data Img. Furthermore, when a printing process is performed, the control unit 2 generates signals, such as a waveform designation signal dCom, for controlling the drive signal generation unit 5. Furthermore, when a printing process is performed, the control unit 2 generates signals, such as a carriage transport control signal SK and a medium transport control signal SB, for controlling the transport unit 9. In this way, during the printing process, the control unit 2 controls the transport unit 9 to move the liquid ejection unit 3 and the recording paper PP, while also adjusting the presence or absence of ink ejection from the ejection section D, the timing of ink ejection, and the like, and controls each part of the inkjet printer 1 so that an image corresponding to the print data Img is formed on the recording paper PP.

[0019] As shown in FIG. 1, the liquid ejection unit 3 includes a supply circuit 31 and a liquid ejection head 32.

[0020] The liquid ejection head 32 has M ejection units D. Here, the value M is a natural number that satisfies "M≧1." Note that, hereinafter, the mth ejection unit D of the M ejection units D provided in the liquid ejection head 32 may be referred to as ejection unit D[m]. Here, the variable m is a natural number that satisfies "1≦m≦M." Furthermore, hereinafter, when a component or signal of the inkjet printer 1 corresponds to a ejection unit D[m] among the M ejection units D, the subscript [m] may be added to the symbol representing the component or signal. The supply circuit 31 switches whether to supply the drive signal Com to the discharge section D[m] based on the designation signal SI. Hereinafter, the drive signal Com supplied to the discharge section D[m] may be referred to as the supply drive signal Vin[m].

[0021] As shown in FIG. 1, the transport unit 9 includes a carriage transport motor 91 and a medium transport motor 92.

[0022] The carriage transport motor 91 transports a carriage 110, which will be described later, based on a carriage transport control signal SK. The medium transport motor 92 transports the recording paper PP based on the medium transport control signal SB.

[0023] FIG. 2 is a perspective view showing an example of the general internal structure of the inkjet printer 1. As shown in FIG.

[0024] 2, the first embodiment assumes that the inkjet printer 1 is a serial printer. Specifically, when performing a printing process, the inkjet printer 1 transports the recording paper PP in the X1 direction, while moving the liquid ejection unit 3 in the Y1 direction that intersects the X1 direction, or in the Y2 direction opposite the Y1 direction, and ejects ink from the liquid ejection unit 3 to form an image on the recording paper PP according to the print data Img.

[0025] Hereinafter, the X1 direction and its opposite X2 direction will be collectively referred to as the "X-axis direction," the Y1 direction intersecting the X-axis direction and its opposite Y2 direction will be collectively referred to as the "Y-axis direction," and the Z1 direction intersecting the X-axis and Y-axis directions and its opposite Z2 direction will be collectively referred to as the "Z-axis direction." In the first embodiment, as an example, a description will be given assuming that the X-axis, Y-axis, and Z-axis directions are perpendicular to one another. However, the present invention is not limited to this aspect. The X-axis, Y-axis, and Z-axis directions may intersect one another. In the first embodiment, the Z1 direction is the direction in which ink is ejected from the ejection section D.

[0026] 2, the inkjet printer 1 according to the first embodiment includes a housing 100 and a carriage 110 that can move back and forth in the Y-axis direction within the housing 100. The carriage 110 is equipped with four liquid ejection units 3 and four drive signal generation units 5.

[0027] As shown in FIG. 2, the first embodiment assumes that the carriage 110 is equipped with four ink cartridges 120, each corresponding to one of the four colors of ink: cyan, magenta, yellow, and black. Furthermore, as described above, the first embodiment assumes that the carriage 110 is equipped with four liquid ejection units 3, each corresponding to one of the four ink cartridges 120. Each ejection section D[m] receives a supply of ink from the ink cartridge 120 corresponding to the liquid ejection unit 3 in which the ejection section D[m] is provided. This allows each ejection section D[m] to be filled with the supplied ink, and to eject the ink filled inside the ejection section D[m] from the nozzle N provided in the ejection section D[m]. The ink cartridges 120 may be provided outside the carriage 110.

[0028] As described above, the inkjet printer 1 according to the first embodiment also includes a transport unit 9. As shown in Fig. 2, the transport unit 9 includes a carriage transport motor 91 for reciprocating the carriage 110 in the Y-axis direction, a carriage guide shaft 96 that supports the carriage 110 so that it can reciprocate in the Y-axis direction, a belt 97 that transports the carriage 110 in the Y-axis direction based on the drive of the carriage transport motor 91, a medium transport motor 92 for transporting the recording paper PP in the X1 direction, a medium transport mechanism 93 that rotates based on the drive of the medium transport motor 92 to transport the recording paper PP in the X1 direction, and a platen 95 that is provided on the Z1 side of the carriage 110 and supports the recording paper PP. Therefore, when a printing process is performed, the transport unit 9 uses the carriage transport motor 91 to move the liquid ejection unit 3 and the carriage 110 back and forth in the Y-axis direction along the carriage guide shaft 96, and the medium transport motor 92 to transport the recording paper PP on the platen 95 in the X1 direction, thereby changing the relative position of the recording paper PP with respect to the liquid ejection unit 3 and enabling ink to land on the entire recording paper PP. In the first embodiment, the carriage transport motor 91 is an example of a "motor."

[0029] FIG. 3 is a schematic partial cross-sectional view of the liquid ejection head 32 cut so as to include the ejection portion D[m].

[0030] As shown in FIG. 3, the ejection portion D[m] includes a piezoelectric element PZ[m], a cavity CV filled with ink inside, a nozzle N communicating with the cavity CV, and a diaphragm 321. When the piezoelectric element PZ[m] is driven by a supply drive signal Vin[m], the ink in the cavity CV is ejected from the nozzle N. The cavity CV is a space partitioned by a cavity plate 324, a nozzle plate 323 in which the nozzle N is formed, and the diaphragm 321. The cavity CV communicates with a reservoir 325 via an ink supply port 326. The reservoir 325 communicates with an ink cartridge 120 corresponding to the ejection portion D[m] via an ink inlet 327. The piezoelectric element PZ[m] has an upper electrode Zu[m], a lower electrode Zd[m], and a piezoelectric body Zm[m] provided between the upper electrode Zu[m] and the lower electrode Zd[m]. The lower electrode Zd[m] is electrically connected to a power supply line Ld set to a predetermined potential VBS. When a supply drive signal Vin[m] is supplied to the upper electrode Zu[m] and a voltage is applied between the upper electrode Zu[m] and the lower electrode Zd[m], the piezoelectric element PZ[m] is displaced in the Z1 direction and the Z2 direction according to the applied voltage, and as a result, the piezoelectric element PZ[m] vibrates. The lower electrode Zd[m] is joined to the diaphragm 321. Therefore, when the piezoelectric element PZ[m] is driven by the supply drive signal Vin[m] and vibrates, the diaphragm 321 also vibrates. Then, the vibration of the diaphragm 321 changes the volume of the cavity CV and the pressure inside the cavity CV, and the ink filled in the cavity CV is ejected from the nozzle N. A part of the ink ejected from the nozzle N is atomized and floats inside the housing 100. In the first embodiment, the piezoelectric element PZ[m] is an example of a “drive element”.

[0031] <<Configuration of the drive signal generation circuit 4>> An example of the configuration of the drive signal generation circuit 4 provided in the drive signal generation unit 5 will be described below with reference to FIG.

[0032] FIG. 4 is a diagram showing an example of the circuit configuration of the drive signal generating circuit 4. As shown in FIG.

[0033] As shown in FIG. 4, the drive signal generating circuit 4 includes an integrated circuit 40, an amplifier circuit 41, a smoothing circuit 42, a pull-up circuit 43, and a filter circuit 44, and generates the drive signal Com based on the waveform designation signal dCom.

[0034] The integrated circuit 40 is, for example, an LSI (Large Scale Integration), and generates gate signals SG1 and SG2 based on the waveform designation signal dCom. Here, the gate signal SG1 is an example of a "first control signal," and the gate signal SG2 is an example of a "second control signal."

[0035] The integrated circuit 40 includes an analog conversion circuit 402 , a subtractor 404 , an adder 406 , an attenuator 408 , an integrating attenuator 412 , a comparator 420 , and a gate driver 430 .

[0036] The analog conversion circuit 402 is a DAC (digital to analog converter) that converts the digital waveform specification signal dCom into an analog signal Aa. The voltage amplitude of the signal Aa is, for example, about 0 to 2 volts, and this voltage is amplified by about 20 times to become the drive signal Com. In other words, the signal Aa is the drive signal Com before amplification. The integrating attenuator 412 attenuates and integrates a signal SN1 input to a terminal Tn1, which will be described later, and outputs the resulting signal Ax. The subtractor 404 outputs a signal Ab indicating the potential obtained by subtracting the potential of the signal Aa from the potential of the signal Ax. The attenuator 408 outputs a signal Ay obtained by attenuating the high frequency components of a signal SN2 input to a terminal Tn2, which will be described later. The adder 406 outputs a signal As indicating the potential obtained by adding the potential of the signal Ab and the potential of the signal Ay.

[0037] The comparator 420 outputs a modulated signal Ms obtained by pulse-modulating the signal As. Specifically, the comparator 420 outputs a modulated signal Ms that goes high when the signal As is at or above a threshold voltage Vth1 if the signal As is rising in voltage, and goes low when the signal As is below a threshold voltage Vth2 if the signal As is falling in voltage. The threshold voltages Vth1 and Vth2 are set to have the relationship "Vth1>Vth2."

[0038] The power supply voltage of the circuit from the analog conversion circuit 402 to the comparator 420 is a low voltage, such as 3.3 volts. In contrast, the drive signal Com has a large amplitude, and may exceed 40 volts, for example. For this reason, the integral attenuator 412 attenuates the signal SN1, which has an amplitude corresponding to the drive signal Com, so that the amplitude range of the signal Ax matches the amplitude range of the signal in the circuit from the analog conversion circuit 402 to the comparator 420.

[0039] In the first embodiment, a digital signal is used as the waveform specification signal dCom, but the waveform specification signal dCom may be any signal that specifies a target value for generating the drive signal Com, and for example, the analog signal Aa may be used as the waveform specification signal dCom. When the signal Aa is the waveform specification signal dCom, the integrated circuit 40 may be configured without including the analog conversion circuit 402.

[0040] The gate driver 430 converts the modulated signal Ms to a specific amplitude to generate a gate signal SG1, and outputs the converted signal to the terminal TnG1. The gate driver 430 also converts the inverted logical level of the modulated signal Ms to a specific amplitude to generate a gate signal SG2, and outputs the converted signal to the terminal TnG2.

[0041] The amplifier circuit 41 includes, for example, transistors Tr1 and Tr2, and generates an amplified signal Az, which is a signal obtained by amplifying the modulation signal Ms, based on gate signals SG1 and SG2 output from the integrated circuit 40. Here, transistor Tr1 is an example of a "first transistor," and transistor Tr2 is an example of a "second transistor." Hereinafter, transistors Tr1 and Tr2 may be collectively referred to as transistors Tr. Note that in the first embodiment, as an example, it is assumed that transistors Tr1 and Tr2 are N-channel field effect transistors, i.e., FETs (Field Effect Transistors).

[0042] 4, a gate signal SG1 output from the gate driver 430 is input to the gate electrode of transistor Tr1 via a terminal TnG1 and a resistor RG1. A gate signal SG2 output from the gate driver 430 is input to the gate electrode of transistor Tr2 via a terminal TnG2 and a resistor RG2. The logic levels of the gate signals SG1 and SG2 are mutually exclusive.

[0043] Here, "mutually exclusive" means that the signal level of the gate signal SG1 supplied to the gate electrode of transistor Tr1 and the signal level of the gate signal SG2 supplied to the gate electrode of transistor Tr2 are never high at the same time; in other words, transistors Tr1 and Tr2 are never on at the same time. Note that transistor Tr1 is turned on when the gate signal SG1 input to the gate electrode of transistor Tr1 is high, and is turned off when the gate signal SG1 input to the gate electrode of transistor Tr1 is low. Transistor Tr2 is turned on when the gate signal SG2 input to the gate electrode of transistor Tr2 is high, and is turned off when the gate signal SG2 input to the gate electrode of transistor Tr2 is low.

[0044] 4, the drain electrode of transistor Tr1 is electrically connected to a power supply line set to a power supply potential VHH, and the source electrode is electrically connected to node Nd. The source electrode of transistor Tr2 is electrically connected to a power supply line set to a reference potential VLL, which is lower than the power supply potential VHH, and the drain electrode is electrically connected to node Nd. Note that the reference potential VLL may be, for example, the ground potential or the same potential as the potential VBS.

[0045] As described above, transistor Tr1 turns on when the gate signal SG1 supplied to its gate electrode is high level, and turns off when it is low level. Transistor Tr2 turns on when the gate signal SG2 supplied to its gate electrode is high level, and turns off when it is low level. Therefore, an amplified signal Az, which is the amplified version of modulated signal Ms, is output to node Nd, which electrically connects the source electrode of transistor Tr1 and the drain electrode of transistor Tr2.

[0046] The smoothing circuit 42 is a low pass filter (LPF) that smoothes the amplified signal Az to generate the drive signal Com. The smoothing circuit 42 includes an inductor L0 and a capacitor C0. The inductor L0 has one end electrically connected to the node Nd and the other end electrically connected to the output terminal Tn-out. Here, the inductor L0 is an example of a "coil." One end of the capacitor C0 is electrically connected to the output terminal Tn-out, and the other end is electrically connected to a power supply line set to a reference potential VLL. The output terminal Tn-out outputs a drive signal Com that is a smoothed version of the amplified signal Az.

[0047] The pull-up circuit 43 pulls up the drive signal Com output from the output terminal Tn-out, and feeds the resulting signal SN1 back to the terminal Tn1. The pull-up circuit 43 includes a resistor R1 having one end electrically connected to the output terminal Tn-out and the other end electrically connected to the terminal Tn1, and a resistor R2 having one end electrically connected to the terminal Tn1 and the other end electrically connected to a power supply line set to the power supply potential VHH.

[0048] The filter circuit 44 is a band pass filter (BPF) that filters out DC components from frequency components in a predetermined band of the drive signal Com to generate a signal SN2, which is then fed back to the terminal Tn2. The filter circuit 44 includes a resistor R3, a capacitor C1 having one end electrically connected to the output terminal Tn-out and the other end electrically connected to one end of the resistor R3, a resistor R4 having one end electrically connected to one end of the resistor R3 and the other end electrically connected to a power supply line set at a reference potential VLL, a capacitor C2 having one end electrically connected to the other end of the resistor R3 and the other end electrically connected to the power supply line set at the reference potential VLL, and a capacitor C3 having one end electrically connected to the other end of the resistor R3 and the other end electrically connected to the terminal Tn2. The capacitor C1 and the resistor R4 function as a high pass filter (HPF) that passes high frequency components of the drive signal Com that are equal to or higher than the cutoff frequency. The resistor R3 and capacitor C2 function as an LPF (Low Pass Filter) that passes low-frequency components of the drive signal Com that are equal to or lower than the cutoff frequency. In the first embodiment, the cutoff frequency of the HPF in the filter circuit 44 is set lower than the cutoff frequency of the LPF. Therefore, the filter circuit 44 passes frequency components of the drive signal Com that are in a predetermined band that are equal to or higher than the cutoff frequency of the HPF and lower than the cutoff frequency of the LPF. In addition, since the filter circuit 44 includes the capacitor C3, the filter circuit 44 feeds back to the terminal Tn2 a signal in which DC components have been removed from the signal of the predetermined band of frequency components that has passed through the HPF and LPF.

[0049] In this way, the drive signal generation circuit 4 generates the drive signal Com by smoothing the amplified signal Az at the node Nd using the smoothing circuit 42. The drive signal Com is integrated and subtracted by the integrating attenuator 412 and then fed back to the subtractor 404. Therefore, the drive signal Com self-oscillates at a frequency determined by the delay in the smoothing circuit 42, the delay in the integrating attenuator 412, and the feedback transfer function. However, because the delay in the feedback path via the terminal Tn1 is large, the frequency of the self-oscillation cannot be increased enough to ensure sufficient waveform accuracy of the drive signal Com using only the feedback via the terminal Tn1. In contrast, in the first embodiment, a path is provided via the terminal Tn2 that feeds back the high-frequency components of the drive signal Com, separate from the path via the terminal Tn1, thereby reducing the feedback delay throughout the drive signal generation circuit 4. That is, in the first embodiment, the frequency of the signal As obtained by adding the signal Ay, which is the high-frequency component of the drive signal Com, to the signal Ab can be made higher than when there is no path via the terminal Tn2, thereby making it possible to sufficiently ensure the accuracy of the drive signal Com.

[0050] In the first embodiment, it is assumed that the drive signal Com contains frequency components of 50 kHz or higher. When the drive signal Com contains frequency components of 50 kHz or higher, as in the first embodiment, setting the frequency of the modulation signal Ms lower than 1 MHz will cause the edges of the waveform of the drive signal Com to become dull, reducing the accuracy of the waveform of the drive signal Com. Furthermore, if the accuracy of the waveform of the drive signal Com decreases, the accuracy of ink ejection from the ejection section D may decrease, potentially reducing the quality of images formed by the inkjet printer 1. Therefore, in order to generate the drive signal Com as a signal having a waveform that accurately reproduces the waveform specified by the waveform specification signal dCom, the frequency of the modulation signal Ms must be 1 MHz or higher. In other words, in order to generate the drive signal Com as a signal having a waveform that accurately reproduces the waveform specified by the waveform specification signal dCom, the oscillation frequency of the self-excited oscillation of the drive signal generation circuit 4 and the drive frequencies of the transistors Tr1 and Tr2 must be 1 MHz or higher. For this reason, in the first embodiment, the frequency of the modulation signal Ms is set to 1 MHz or more, so that the frequencies of the gate signals SG1 and SG2 are set to 1 MHz or more, and the drive frequencies of the transistors Tr1 and Tr2 are set to 1 MHz or more. This makes it possible to make the waveform of the drive signal Com a waveform that accurately reproduces the waveform specified by the waveform specification signal dCom, and suppresses any deterioration in the accuracy of ink ejection from the ejection section D.

[0051] When the frequency of the modulation signal Ms increases, the switching losses in the transistors Tr1 and Tr2 increase. When the switching losses in the transistors Tr1 and Tr2 increase, the power consumption in the drive signal generation circuit 4 increases, and the amount of heat generated in the drive signal generation circuit 4 increases. From the perspective of reducing the switching losses in the transistor Tr, it is preferable that the drive frequency of the transistor Tr is 8 MHz or less, and more preferably 4 MHz or less. Therefore, in the first embodiment, by setting the frequency of the modulation signal Ms to 8 MHz or less, the frequencies of the gate signal SG1 and the gate signal SG2 are set to 8 MHz or less, and the drive frequencies of the transistors Tr1 and Tr2 are set to 8 MHz or less. Thereby, according to the first embodiment, it becomes possible to achieve both an improvement in the waveform accuracy of the drive signal Com and power saving of the drive signal generation circuit 4.

[0052] <<A.3. Configuration and Operation of the Liquid Discharge Unit 3>> Hereinafter, an example of the configuration and operation of the liquid discharge unit 3 will be described while referring to FIGS. 5 to 7.

[0053] FIG. 5 is a block diagram showing an example of the configuration of the liquid discharge unit 3.

[0054] As shown in FIG. 5, the liquid discharge unit 3 includes a supply circuit 31 and a liquid discharge head 32. The liquid discharge unit 3 also includes a wiring LC through which a drive signal Com is supplied from the drive signal generation unit 5.

[0055] <00—0231>As shown in FIG. 5, the supply circuit 31 includes M discharge parts D[1] to D[M], M switches WS[1] to WS[M] that correspond one-to-one to the M discharge parts, and a connection state designation circuit 310 that designates the connection state of each switch. The connection state designation circuit 310 generates a connection state designation signal QS[m] that designates the on / off of the switch WS[m] based on at least some of the signals of the designation signal SI, the latch signal LAT, and the change signal CH supplied from the control unit 2. The switch WS[m] switches between conduction and non-conduction between the wiring LC and the upper electrode Zu[m] of the piezoelectric element PZ[m] provided in the discharge section D[m] based on the connection state designation signal QS[m]. In the first embodiment, the switch WS[m] is turned on when the connection state designation signal QS[m] is at a high level and turned off when the connection state designation signal QS[m] is at a low level. When the switch WS[m] is turned on, the drive signal Com supplied to the wiring LC is supplied to the upper electrode Zu[m] of the discharge section D[m] as the supply drive signal Vin[m].

[0056] FIG. 6 is a timing chart showing various signals such as the drive signal Com supplied to the liquid ejection unit 3. As shown in FIG.

[0057] 6, when the inkjet printer 1 executes a printing process, one or more unit periods TP are set as the operating period of the inkjet printer 1. In the first embodiment, the inkjet printer 1 can drive each discharge section D[m] for the printing process during each unit period TP.

[0058] As shown in Figure 6, the control unit 2 outputs a latch signal LAT having a pulse PLL. As a result, the control unit 2 defines a unit period TP as the period from the rising edge of the pulse PLL to the rising edge of the next pulse PLL. The control unit 2 also outputs a change signal CH having a pulse PLC during the unit period TP. The control unit 2 then divides the unit period TP into a drive period TQ1 from the rising edge of the pulse PLL to the rising edge of the pulse PLC, and a drive period TQ2 from the rising edge of the pulse PLC to the rising edge of the pulse PLL.

[0059] As shown in FIG. 6, the designation signal SI includes M individual designation signals Sd[1] to Sd[M] that correspond one-to-one to the M discharge sections D[1] to D[M]. The individual designation signal Sd[m] designates the drive mode of the discharge section D[m] during each unit period TP when the inkjet printer 1 executes a printing process. Prior to each unit period TP, the control unit 2 synchronizes the designation signal SI, including the M individual designation signals Sd[1] to Sd[M], with the clock signal CL and supplies it to the connection state designation circuit 310. The connection state designation circuit 310 then generates a connection state designation signal QS[m] during that unit period TP based on the individual designation signal Sd[m].

[0060] In the first embodiment, it is assumed that during the unit period TP in which the printing process is executed, the ejection section D[m] can form any of the following dots: a large dot made of ink with an ink amount ξ1, a medium dot made of ink with an ink amount ξ2 that is less than the ink amount ξ1, or a small dot made of ink with an ink amount ξ3 that is less than the ink amount ξ2.

[0061] FIG. 7 is an explanatory diagram for explaining an example of the individual designation signal Sd[m].

[0062] As shown in Figure 7, in the first embodiment, the individual designation signal Sd[m] can take any one of four values ​​during the unit period TP in which the printing process is executed: the value "1" that designates the discharge section D[m] as a large dot-forming discharge section DP-1; the value "2" that designates the discharge section D[m] as a medium dot-forming discharge section DP-2; the value "3" that designates the discharge section D[m] as a small dot-forming discharge section DP-3; and the value "4" that designates the discharge section D[m] as a non-dot-forming discharge section DP-N. Here, the large-dot-forming discharge section DP-1 is a discharge section D that forms large dots in the unit period TP. The medium-dot-forming discharge section DP-2 is a discharge section D that forms medium dots in the unit period TP. The small-dot-forming discharge section DP-3 is a discharge section D that forms small dots in the unit period TP. The non-dot-forming discharge section DP-N is a discharge section D that does not form dots in the unit period TP.

[0063] Returning to the explanation in FIG. As shown in FIG. 6, in the first embodiment, the drive signal Com has a waveform PA1 provided in the drive period TQ1 and a waveform PA2 provided in the drive period TQ2. Of these, the waveform PA1 is a waveform that goes from a potential V0 to a potential VLA1 that is lower than the potential V0, through a potential VHA1 that is higher than the potential V0, and then returns to the potential V0. The waveform PA1 is determined so that when a supply drive signal Vin[m] having the waveform PA1 is supplied to the discharge section D[m], ink equivalent to an ink amount φ1 is ejected from the discharge section D[m]. The waveform PA2 is a waveform that goes from a potential V0 to a potential VLA2 that is lower than the potential V0, through a potential VHA2 that is higher than the potential V0, and then returns to the potential V0. The waveform PA2 is determined so that when a supply drive signal Vin[m] having the waveform PA2 is supplied to the discharge section D[m], ink equivalent to an ink amount φ2 is ejected from the discharge section D[m]. In the first embodiment, it is assumed that the ink amount ξ1 corresponds to the sum of the ink amount φ1 and the ink amount φ2, the ink amount ξ2 corresponds to the ink amount φ1, and the ink amount ξ3 corresponds to the ink amount φ2.

[0064] In the first embodiment, as an example, it is assumed that when the potential of the supply drive signal Vin[m] supplied to the ejection section D[m] is high, the volume of the cavity CV of the ejection section D[m] is smaller than when the potential is low. Therefore, when the ejection section D[m] is driven by the supply drive signal Vin[m] having the waveform PA1 or the like, the potential of the supply drive signal Vin[m] changes from low to high, causing the ink in the ejection section D[m] to be ejected from the nozzle N.

[0065] 7, when the individual designation signal Sd[m] indicates a value of "1" that designates the discharger D[m] as the large-dot-forming discharger DP-1 during the unit period TP, the connection state designation circuit 310 sets the connection state designation signal QS[m] to a high level during the drive periods TQ1 and TQ2. In this case, the switch WS[m] is turned on during the drive periods TQ1 and TQ2. Therefore, during the unit period TP, the discharger D[m] is driven by the supply drive signal Vin[m] having waveforms PA1 and PA2, and discharges ink of an ink amount ξ1 corresponding to a large dot. Furthermore, if the individual designation signal Sd[m] indicates a value of "2" that designates the discharger D[m] as the medium-dot-forming discharger DP-2 during the unit period TP, the connection state designation circuit 310 sets the connection state designation signal QS[m] to a high level during the drive period TQ1. In this case, the switch WS[m] is turned on during the drive period TQ1. As a result, the discharger D[m] is driven by the supply drive signal Vin[m] having the waveform PA1 during the unit period TP, and discharges ink at an ink volume ξ2 corresponding to a medium dot. Furthermore, if the individual designation signal Sd[m] indicates a value of "3" during the unit period TP, which designates the discharge unit D[m] as the small-dot-forming discharge unit DP-3, the connection state designation circuit 310 sets the connection state designation signal QS[m] to a high level during the drive period TQ2. In this case, the switch WS[m] is turned on during the drive period TQ2. Therefore, during the unit period TP, the discharge unit D[m] is driven by the supply drive signal Vin[m] having the waveform PA2, and discharges ink at an ink volume ξ3 corresponding to a small dot. Furthermore, when the individual designation signal Sd[m] indicates a value of "4" that designates the discharge unit D[m] as a non-dot-forming discharge unit DP-N during the unit period TP, the connection state designation circuit 310 sets the connection state designation signal QS[m] to a low level throughout the unit period TP. In this case, the switch WS[m] is turned off throughout the unit period TP. Therefore, the discharge unit D[m] is not driven by the supply drive signal Vin[m] during the unit period TP, and does not discharge ink.

[0066] <<Configuration of Drive Signal Generation Unit 5>> Hereinafter, the configuration of the drive signal generation unit 5 will be described while referring to FIG. 8.

[0067] FIG. 8 is a cross-sectional view showing an example of the configuration of the drive signal generation unit 5 when the drive signal generation unit 5 is cut by a plane that is a plane with the X-axis direction as the normal direction and intersects the transistor Tr. In the first embodiment, as an example, a case where the transistor Tr1 and the transistor Tr2 have the same structure is assumed.

[0068] As shown in FIG. 8, the transistor Tr is provided on a substrate 51 included in the drive signal generation unit 5. Specifically, in the first embodiment, it is assumed that the substrate 51 is a flat plate-shaped member extending with the Z-axis direction as the normal direction, and has two surfaces with the Z-axis direction as the normal direction, namely, a surface 511 facing the Z1 direction and a surface 512 facing the Z2 direction. And in the first embodiment, a case where the transistor Tr is provided on the surface 512 of the substrate 51 is assumed.

[0069] The transistor Tr includes a chip main body portion 60, a gate electrode 61g, a source electrode 61s, and a drain electrode 61d.

[0070] The chip main body portion 60 is a portion called a so-called die, and for example, has a substantially rectangular parallelepiped shape. In the first embodiment, it is assumed that the chip main body portion 60 has two surfaces with the Z-axis direction as the normal direction, namely, a surface 601 facing the Z1 direction and a surface 602 facing the Z2 direction.

[0071] Also, in the first embodiment, as an example, a case where the source electrode 61s and the drain electrode 61d are provided on the surface 601 of the chip main body portion 60 and the gate electrode 61g is provided on the surface 602 is assumed.

[0072] A plurality of gate connection terminals 62g are provided on the surface 512 of the substrate 51 so as to correspond to the plurality of transistors Tr included in the drive signal generating unit 5. The gate electrode 61g is electrically connected to the gate connection terminal 62g provided corresponding to the transistor Tr including the gate electrode 61g. In the first embodiment, it is assumed, as an example, that the gate electrode 61g is electrically connected to the gate connection terminal 62g via a wire 64.

[0073] Each gate connection terminal 62g is electrically connected to the integrated circuit 40. Specifically, the gate connection terminal 62g provided corresponding to the transistor Tr1 is electrically connected to a terminal TnG1 of the integrated circuit 40 via a resistor RG1. Furthermore, the gate connection terminal 62g provided corresponding to the transistor Tr2 is electrically connected to a terminal TnG2 of the integrated circuit 40 via a resistor RG2.

[0074] A plurality of source connection terminals 62s are provided on the surface 512 of the substrate 51 so as to correspond to the plurality of transistors Tr included in the drive signal generating unit 5. The source electrodes 61s are electrically connected to the source connection terminals 62s provided corresponding to the transistors Tr having the source electrodes 61s. In the first embodiment, as an example, it is assumed that the source electrodes 61s are directly connected to the source connection terminals 62s.

[0075] Each source connection terminal 62s is electrically connected to the node Nd or a power supply line set to the reference potential VLL. Specifically, the source connection terminal 62s provided corresponding to the transistor Tr1 is electrically connected to the node Nd. Furthermore, the source connection terminal 62s provided corresponding to the transistor Tr2 is electrically connected to a power supply line set to the reference potential VLL.

[0076] A plurality of drain connection terminals 62d are provided on the surface 512 of the substrate 51 so as to correspond to the plurality of transistors Tr included in the drive signal generating unit 5. The drain electrodes 61d are electrically connected to the drain connection terminals 62d provided corresponding to the transistors Tr having the drain electrodes 61d. In the first embodiment, as an example, it is assumed that the drain electrodes 61d are directly connected to the drain connection terminals 62d.

[0077] Each drain connection terminal 62d is electrically connected to the node Nd or a power supply line set to the power supply potential VHH. Specifically, the drain connection terminal 62d provided corresponding to the transistor Tr1 is electrically connected to a power supply line set to the power supply potential VHH. Furthermore, the drain connection terminal 62d provided corresponding to the transistor Tr2 is electrically connected to the node Nd.

[0078] A heat sink 52 is attached to the surface 511 of the substrate 51. The heat sink 52 includes a body portion 520 and a coating portion 521.

[0079] The main body portion 520 is made of copper or aluminum, and is composed of a base portion 5201 , a fin 5202 , and a fin 5203 .

[0080] Of these, the base 5201 extends on a plane PL1 having a normal direction in the Z-axis direction. The fin 5202 is connected to a connection portion PY1 of the base 5201, and extends on a plane PL2 having a normal direction in the Y-axis direction. The fin 5203 is connected to a connection portion PY2 of the base 5201 that is located in the Y1 direction as viewed from the connection portion PY1, and extends on a plane PL3 having a normal direction in the Y-axis direction. That is, in the first embodiment, the heat sink 52 has two fins. In addition, in the first embodiment, the base portion 5201 is an example of the "first plate-shaped portion", the fin 5202 is an example of the "second plate-shaped portion", the fin 5203 is an example of the "third plate-shaped portion", the plane PL1 is an example of the "first plane", the plane PL2 is an example of the "second plane", the plane PL3 is an example of the "third plane", the connection portion PY1 is an example of the "first portion", and the connection portion PY2 is an example of the "second portion".

[0081] The coating portion 521 is composed of graphene and coats the main body portion 520. Specifically, the coating portion 521 coats at least all the surfaces of the fins 5202 and 5203 and the surface of the base portion 5201 in the Z1 direction among the surfaces of the main body portion 520.

[0082] Here, graphene is a sheet-like substance composed of carbon atoms. Hereinafter, among graphene, a sheet-like substance having a thickness of one carbon atom will be referred to as a graphene sheet. In the first embodiment, it is assumed that the coating portion 521 is composed of a plurality of layers of graphene sheets.

[0083] <<A.5. Conventional Example>> Hereinafter, while explaining the drive signal generation unit 5W according to the conventional example with reference to FIGS. 9 and 10, the effects of the drive signal generation unit 5 according to the first embodiment will be described.

[0084] FIG. 9 is a cross-sectional view showing an example of the configuration of the drive signal generation unit 5W when the drive signal generation unit 5W is cut by a plane that is a plane with the X-axis direction as the normal direction and intersects the transistor Tr. [[ID=ip19]]

[0085] As shown in FIG. 9 , the drive signal generating unit 5W has the same configuration as the drive signal generating unit 5 according to the first embodiment, except that it includes a heat sink 52W instead of the heat sink 52. The heat sink 52W differs from the heat sink 52 according to the first embodiment in that it includes a main body portion 520W instead of the main body portion 520 and in that it does not include the coating portion 521. Like the main body portion 520, the main body portion 520W is formed from copper or aluminum. The main body portion 520W has the same configuration as the main body portion 520 according to the first embodiment, except that it includes three or more fins 520F instead of the fins 5202 and 5203. Specifically, the main body portion 520W includes ten or more fins 520F. Each fin 520F is a flat plate-shaped member extending such that its normal direction is the Z-axis direction.

[0086] FIG. 10 is a diagram showing the results of measuring the temperatures of the drive signal generating units 5 and 5W, and the results of measuring the weights of the heat sink 52 and 52W.

[0087] As shown in FIG. 10 , when the drive signal generating unit 5 according to the first embodiment has a 10 W heat source, the temperature of the drive signal generating unit 5 having the heat sink 52 is 85 degrees. On the other hand, when the drive signal generating unit 5W according to the conventional example has a 10 W heat source, the temperature of the drive signal generating unit 5W having the heat sink 52W is 86 degrees. In this way, the temperature of the drive signal generating unit 5 having the heat sink 52 and the temperature of the drive signal generating unit 5W having the heat sink 52W are substantially the same. Here, “substantially the same” includes not only cases where they are completely identical, but also cases where they can be considered to be the same when tolerances are taken into account, such as when they are identical in design but differ due to manufacturing tolerances, and when they are identical in specifications but differ due to tolerances caused by disturbances or the like. In the first embodiment, “substantially the same” is a concept that includes cases where they can be considered to be the same when tolerances of about 10% are taken into account.

[0088] 10, the heat sink 52 according to the first embodiment has two fins and weighs 35 g. On the other hand, the heat sink 52W according to the conventional example has 16 fins and weighs 150 g.

[0089] As described above, the heat sink 52 according to the first embodiment has only two fins, which significantly reduces its weight compared to a heat sink 52W having ten or more fins. Specifically, the weight of the heat sink 52 according to the first embodiment can be reduced by approximately 25% compared to a conventional heat sink 52W. Therefore, according to the first embodiment, when the drive signal generation unit 5 is mounted on the carriage 110 and moved, the load on the carriage transport motor 91 that drives the carriage 110 can be reduced compared to when the drive signal generation unit 5W according to the conventional example is mounted on the carriage 110 and moved. In other words, the drive signal generation unit 5 according to the first embodiment extends the life of the carriage transport motor 91 and reduces the amount of power required to drive the carriage transport motor 91 compared to when the drive signal generation unit 5W according to the conventional example is mounted on the carriage 110.

[0090] Furthermore, because the heat sink 52 according to the first embodiment has a surface coated with graphene, it has superior heat dissipation properties compared to the heat sink 52W according to the conventional example, which is not coated with graphene. Therefore, the heat sink 52 according to the first embodiment can maintain the temperature of the drive signal generation unit 5 at approximately the same temperature as the drive signal generation unit 5W to which the heat sink 52 is attached, despite having a significantly smaller number of fins compared to the heat sink 52W according to the conventional example. In other words, the heat sink 52 according to the first embodiment can more easily achieve both weight reduction and improved heat dissipation properties compared to the heat sink 52W according to the conventional example.

[0091] Further, since the surface of the heat sink 52 according to the first embodiment is coated with graphene, the possibility of the heat sink 52 being corroded by the ink mist can be reduced as compared with the heat sink 52W according to the conventional example without the coating by graphene. Therefore, the heat sink 52 according to the first embodiment can suppress the decrease in heat dissipation performance due to the corrosion of the heat sink 52 as compared with the heat sink 52W according to the conventional example, and can maintain high heat dissipation performance over a long period of time.

[0092] <<B. Second Embodiment>> Hereinafter, the inkjet printer 1 according to the second embodiment will be described while referring to FIGS. 11 and 12. In each of the embodiments illustrated below, for elements whose operations and functions are the same as those of the first embodiment, the reference numerals used in the description of the first embodiment are reused and the detailed description of each is appropriately omitted.

[0093] FIG. 11 is a cross-sectional view showing an example of the configuration of a drive signal generation unit 5B included in the inkjet printer 1 according to the second embodiment. Specifically, FIG. 11 is a cross-sectional view showing an example of the configuration of the drive signal generation unit 5B when the drive signal generation unit 5B is cut by a plane that is a plane with the X-axis direction as the normal direction and intersects the transistor Tr-B. The inkjet printer 1 according to the second embodiment is configured in the same manner as the inkjet printer 1 according to the first embodiment, except that it includes a drive signal generation unit 5B instead of the drive signal generation unit 5. Further, in the second embodiment, the transistors Tr1 and Tr2 shown in FIG. 4 are collectively referred to as the transistor Tr-B.

[0094] As shown in FIG. 11, the drive signal generation unit 5B is configured in the same manner as the drive signal generation unit 5 according to the first embodiment, except that it includes a transistor Tr-B instead of the transistor Tr, includes a mold member 55, and includes a clip 63.

[0095] The transistor Tr-B is configured in the same manner as the transistor Tr of the first embodiment, except that a source electrode 61s is provided on surface 601 of the chip main body 60, and a gate electrode 61g and a drain electrode 61d are provided on surface 602.

[0096] A plurality of gate connection terminals 62g are provided on the surface 512 of the substrate 51 so as to correspond to the plurality of transistors Tr-B of the drive signal generating unit 5B. The gate electrode 61g is electrically connected to the gate connection terminal 62g provided corresponding to the transistor Tr-B having the gate electrode 61g. In the second embodiment, as an example, it is assumed that the gate electrode 61g is electrically connected to the gate connection terminal 62g via a wire 64.

[0097] A plurality of source connection terminals 62s are provided on the surface 512 of the substrate 51 so as to correspond to the plurality of transistors Tr-B of the drive signal generating unit 5B. The source electrodes 61s are electrically connected to the source connection terminals 62s provided corresponding to the transistors Tr-B having the source electrodes 61s. In the second embodiment, as an example, it is assumed that the source electrodes 61s are directly connected to the source connection terminals 62s.

[0098] A plurality of drain connection terminals 62d are provided on the surface 512 of the substrate 51 so as to correspond to the plurality of transistors Tr-B of the drive signal generating unit 5B. The drain electrode 61d is electrically connected to the drain connection terminal 62d provided corresponding to the transistor Tr-B having the drain electrode 61d. In the second embodiment, as an example, it is assumed that the drain electrode 61d is electrically connected to the drain connection terminal 62d via a clip 63.

[0099] Here, the clip 63 is a component made of a metal such as copper. That is, in the second embodiment, it is assumed that the transistor Tr-B (that is, the transistor Tr1 and the transistor Tr2) has a Cu clip structure.

[0100] The molding member 55 is made of an insulating material such as resin. The molding member 55 is provided on the surface 512 of the substrate 51 so as to seal the transistor Tr-B. In the second embodiment, as an example, it is assumed that the molding member 55 is provided on the surface 512 of the substrate 51 so as to cover the transistor Tr-B, the clip 63, and the wire 64.

[0101] In the second embodiment, it is assumed that a reaction liquid can be ejected from some of the ejection sections D of the multiple ejection sections D provided in the liquid ejection unit 3. Here, the reaction liquid is a liquid for fixing the ink to the recording paper PP. In the second embodiment, the inkjet printer 1 ejects ink onto the recording paper PP from one of the ejection sections D provided in the liquid ejection unit 3, and then ejects reaction liquid onto the recording paper PP from another of the ejection sections D provided in the liquid ejection unit 3, thereby fixing the ink adhered to the recording paper PP to the recording paper PP. In the second embodiment, the reaction liquid is another example of "liquid."

[0102] FIG. 12 is a diagram showing an example of the composition and physical properties of the reaction liquid according to the second embodiment.

[0103] As shown in Figure 12, the reaction solution contains 19% by mass of calcium nitrate tetrahydrate as a flocculant and 0.6% by mass of a silicone surfactant as a surfactant. The reaction solution also contains 3% by mass of 1,2-hexanediol, 15% by mass of propylene glycol, 0.1% by mass of tripropanolamine, and 0.1% by mass of 0.1M acetic acid as a solvent, with the remainder containing water to make the total mass 100%. The reaction solution is adjusted to have a flocculant concentration of 0.8 (mol / L), a pH of 3, a viscosity of 4 (mPa·s at 20°C), and a surface tension of 25 (mN / m). The reaction liquid may be a liquid with a pH of "3 or less." Furthermore, the reaction liquid may be "Reaction Liquid H7" disclosed by the present applicant in JP 2016-199001 A.

[0104] As described above, in the second embodiment, the transistor Tr-B has a Cu clip structure. Therefore, in the second embodiment, the areas of the drain electrode 61d and the drain connecting terminal 62d, and the source electrode 61s and the source connecting terminal 62s can be increased compared to an embodiment that does not employ a Cu clip structure. As a result, in the second embodiment, it is possible to ensure high heat dissipation from the transistor Tr-B compared to an embodiment that does not employ a Cu clip structure.

[0105] Furthermore, in the second embodiment, because the transistor Tr-B employs a Cu clip structure, the impact resistance of the transistor Tr-B can be increased compared to an embodiment in which the Cu clip structure is not employed and the drain electrode 61d and the drain connection terminal 62d are connected by the wire 64. As a result, in the second embodiment, even in cases where there is a high possibility of the drive signal generation unit 5B being subjected to an impact, such as when the drive signal generation unit 5B including the transistor Tr-B is mounted on the carriage 110, it is possible to achieve a longer life for the drive signal generation unit 5B compared to an embodiment in which the Cu clip structure is not employed.

[0106] In the second embodiment, a reaction solution with a pH of 3 or less is discharged from the liquid discharge unit 3. And a liquid with a low pH of 3 or less is likely to corrode the metal in the inkjet printer 1 when it adheres to the metal. In contrast, in the second embodiment, since the transistor Tr-B is covered by the mold member 55, the adhesion of ink and the reaction solution to the transistor Tr-B can be reduced as compared with an aspect in which the drive signal generation unit 5B does not include the mold member 55. Therefore, according to the second embodiment, as compared with an aspect in which the drive signal generation unit 5B does not include the mold member 55, the corrosion of the metal such as the wiring and terminals included in the transistor Tr-B is suppressed, and the long life of the transistor Tr-B can be realized.

[0107] In the second embodiment, the transistor Tr-B has been described by way of example in an aspect in which the source electrode 61s is provided on the surface 601 and the gate electrode 61g and the drain electrode 61d are provided on the surface 602 of the chip main body 60. However, the present invention is not limited to such an aspect. For example, in the transistor Tr-B, the drain electrode 61d may be provided on the surface 601 and the gate electrode 61g and the source electrode 61s may be provided on the surface 602 of the chip main body 60. In this case, the drain electrode 61d may be directly connected to the drain connection terminal 62d. Also, in this case, the source electrode 61s may be electrically connected to the source connection terminal 62s via the clip 63. Also, in this case, the gate electrode 61g may be electrically connected to the gate connection terminal 62g via the wire 64.

[0108] Also, in the second embodiment, the gate electrode 61g has been described by way of example in an aspect in which it is electrically connected to the gate connection terminal 62g via the wire 64. However, the present invention is not limited to such an aspect. For example, the gate electrode 61g may be electrically connected to the gate connection terminal 62g via a conductive clip such as the clip 63.

[0109] <<C. Third Embodiment>> An inkjet printer 1 according to the third embodiment will be described below with reference to Figure 13. Note that for elements in the following exemplary embodiments whose actions and functions are similar to those of the first or second embodiment, the reference numerals used in the description of the first or second embodiment will be used, and detailed description of each will be omitted where appropriate.

[0110] Fig. 13 is a cross-sectional view showing an example of the configuration of a drive signal generation unit 5C provided in an inkjet printer 1 according to a third embodiment. Specifically, Fig. 13 is a cross-sectional view showing an example of the configuration of the drive signal generation unit 5C when the drive signal generation unit 5C is cut along a plane whose normal direction is the X-axis direction and which intersects with the transistor Tr-B. The inkjet printer 1 according to the third embodiment has the same configuration as the inkjet printer 1 according to the second embodiment, except that it includes a drive signal generation unit 5C instead of the drive signal generation unit 5. In the third embodiment, as in the second embodiment, the transistors Tr1 and Tr2 shown in Fig. 4 are collectively referred to as transistor Tr-B.

[0111] As shown in FIG. 13, the drive signal generating unit 5C is configured similarly to the drive signal generating unit 5B of the second embodiment, except that it includes a molding member 55C instead of the molding member 55 and a heat sink 56.

[0112] As described above, the transistor Tr-B has a source electrode 61s provided on the surface 601 of the chip body 60, and a gate electrode 61g and a drain electrode 61d provided on the surface 602. The gate electrode 61g is electrically connected to the gate connection terminal 62g via a wire 64. The source electrode 61s is directly connected to the source connection terminal 62s. The drain electrode 61d is electrically connected to the drain connection terminal 62d via a clip 63. That is, in the third embodiment, similar to the second embodiment, it is assumed that the transistor Tr-B (i.e., the transistor Tr1 and the transistor Tr2) has a Cu clip structure.

[0113] The molding member 55C is made of an insulating material such as resin. The molding member 55C is provided on the surface 512 of the substrate 51 so as to seal the transistor Tr-B. In the second embodiment, as an example, it is assumed that the molding member 55C is provided on the surface 512 of the substrate 51 so as to cover the transistor Tr-B and the wire 64 while exposing the surface of the clip 63 in the Z2 direction.

[0114] The heat sink 56 is provided over the Z2 direction surface of the clip 63 and the Z2 direction surface of the molded member 55C. The heat sink 56 includes a main body portion 560 and a coating portion 561.

[0115] The main body 560 is made of copper or aluminum and includes a base 5601 extending in a flat plate shape with the Z-axis direction as its normal direction, fins 5602 extending in a flat plate shape with the Y-axis direction as its normal direction, and fins 5603 extending in a flat plate shape with the Y-axis direction as its normal direction. That is, in the third embodiment, the heat sink 56 includes two fins, similar to the heat sink 52.

[0116] The coating portion 561 is made of graphene and coats the main body portion 560. Specifically, the coating portion 561 coats at least all surfaces of the fins 5602 and 5603 of the main body portion 560 and the surface in the Z2 direction of the base portion 5601 among the surfaces of the main body portion 560. In the third embodiment, it is assumed that the coating portion 561 is made of a plurality of layers of graphene sheets.

[0117] As described above, according to the third embodiment, the drive signal generation unit 5C includes the heat sink 56, and therefore, in addition to heat dissipation in the Z1 direction from the heat sink 52, heat dissipation in the Z2 direction from the heat sink 56 is also possible. Therefore, according to the third embodiment, it is possible to ensure high heat dissipation performance in the drive signal generation unit 5C compared to an embodiment that does not assume heat dissipation in the Z2 direction.

[0118] Furthermore, according to the third embodiment, because the transistor Tr-B is covered by the molding member 55C, adhesion of ink and reaction liquid to the transistor Tr-B can be reduced compared to an embodiment in which the drive signal generation unit 5C does not include the molding member 55C. Therefore, according to the third embodiment, corrosion of metals such as wiring and terminals of the transistor Tr-B can be suppressed, and the life of the transistor Tr-B can be extended, compared to an embodiment in which the drive signal generation unit 5C does not include the molding member 55C. Note that in the third embodiment, a reaction liquid with a pH of 3 or less may be ejected from the liquid ejection unit 3, as in the second embodiment.

[0119] Furthermore, according to the third embodiment, since the transistor Tr-B has a Cu clip structure, the areas of the drain electrode 61d and the drain connecting terminal 62d, and the source electrode 61s and the source connecting terminal 62s can be increased compared to an embodiment that does not employ a Cu clip structure. As a result, in the third embodiment, it is possible to ensure high heat dissipation from the transistor Tr-B compared to an embodiment that does not employ a Cu clip structure.

[0120] Furthermore, the heat sink 56 according to the third embodiment has a surface coated with graphene, and therefore can exhibit superior performance in terms of weight reduction, heat dissipation, and corrosion resistance, compared to an embodiment in which the heat sink 52W according to the conventional example, which is not coated with graphene, is used as the heat sink 56.

[0121] In the third embodiment, the transistor Tr-B has been described by way of example in a mode where the source electrode 61s is provided on the surface 601 and the gate electrode 61g and the drain electrode 61d are provided on the surface 602 of the chip main body 60. However, the present invention is not limited to such a mode. For example, in the transistor Tr-B, the drain electrode 61d may be provided on the surface 601 and the gate electrode 61g and the source electrode 61s may be provided on the surface 602 of the chip main body 60. In this case, the drain electrode 61d may be directly connected to the drain connection terminal 62d. Also, in this case, the source electrode 61s may be electrically connected to the source connection terminal 62s via the clip 63. Further, in this case, the gate electrode 61g may be electrically connected to the gate connection terminal 62g via the wire 64.

[0122] In the third embodiment, the mode in which the gate electrode 61g is electrically connected to the gate connection terminal 62g via the wire 64 has been described by way of example. However, the present invention is not limited to such a mode. For example, the gate electrode 61g may be electrically connected to the gate connection terminal 62g via a conductive clip such as the clip 63.

[0123] In the third embodiment, the mode in which the drive signal generation unit 5C includes the heat sink 52 and the heat sink 56 coated with graphene has been described by way of example. However, the present invention is not limited to such a mode. The drive signal generation unit 5C may include a heat sink 52W instead of the heat sink 52 on the surface 511 of the substrate 51, or may include a heat sink 52W instead of the heat sink 56 on the Z2-direction surface of the clip 63 and the mold member 55C.

[0124] <<D. Variations>> Each of the above embodiments can be variously modified. Specific modification modes are exemplified below. Two or more modes arbitrarily selected from the following examples can be appropriately combined within a non - conflicting range. In the modification examples exemplified below, for elements whose actions and functions are equivalent to those of the embodiments, the reference numerals referred to in the above description are reused, and the detailed description of each is appropriately omitted.

[0125] <<D.1. Modification Example 1>> In the above - described first to third embodiments, the case where the drive signal generation unit 5 and the liquid discharge unit 3 are separate bodies has been exemplified and described. However, the present invention is not limited to such an aspect. The drive signal generation unit 5 may be built in the liquid discharge unit 3.

[0126] FIG. 14 is a functional block diagram showing an example of the configuration of an inkjet printer 1D according to Modification Example 1.

[0127] As shown in FIG. 14, the inkjet printer 1D is configured in the same manner as the inkjet printer 1 according to the first embodiment, except that it includes a liquid discharge unit 3D instead of the liquid discharge unit 3. The liquid discharge unit 3D is configured in the same manner as the liquid discharge unit 3 according to the first embodiment, except that it includes a drive signal generation unit 5. In FIG. 14, an aspect in which the liquid discharge unit 3D includes the drive signal generation unit 5 is exemplified. However, the present invention is not limited to such an aspect. The liquid discharge unit 3D may include a drive signal generation unit 5B instead of the drive signal generation unit 5, or may include a drive signal generation unit 5C instead of the drive signal generation unit 5.

[0128] <<D.2. Modification Example 2>> In the above-described first to third embodiments and Modification 1, the mode in which the mold member 55 or the mold member 55C seals one transistor Tr or one transistor Tr-B has been exemplified and described. However, the present invention is not limited to such a mode. The mold member 55 or the mold member 55C may seal two or more transistors Tr or two or more transistors Tr-B.

[0129] For example, as shown in FIG. 15, the mold member 55 may seal the transistor Tr1 and the transistor Tr2 as one package. Further, for example, as shown in FIG. 16, the mold member 55C may seal the transistor Tr1 and the transistor Tr2 as one package.

[0130] <<D.3. Modification 3>> In the above-described first to third embodiments and Modifications 1 and 2, the case where the inkjet printer 1 includes four liquid ejection units 3 and four drive signal generation units 5 has been assumed. However, the present invention is not limited to such a mode. The inkjet printer 1 may include one or more and three or less liquid ejection units 3 and one or more and three or less drive signal generation units 5, or may include five or more liquid ejection units 3 and five or more drive signal generation units 5.

[0131] <<E. Supplementary Note>> Aspects related to the above description are appended below. For ease of understanding of each aspect, hereinafter, the reference numerals in the drawings are appended in parentheses for convenience, but the present invention is not intended to be limited to the illustrated aspects.

[0132] <<E.1. Supplementary Note 1>> Hereinafter, the inkjet printer 1 according to Supplementary Note 1 will be described.

[0133] <<Supplementary Note 1-1>> The inkjet printer 1 according to Appendix 1-1 comprises a liquid ejection unit 3 that includes a plurality of piezoelectric elements PZ[m] driven by a drive signal Com and ejects ink in response to the driving of the plurality of piezoelectric elements PZ[m], and a drive signal generation unit 5 that generates the drive signal Com, the drive signal generation unit 5 including a substrate 51, a drive signal generation circuit 4 that is disposed on the substrate 51 and generates the drive signal Com, and a heat sink 52 fixed to the substrate 51, the heat sink 52 including a main body portion 520 made of copper or aluminum, and the main body portion 520 being coated with graphene.

[0134] According to Supplementary Note 1-1, since the heat sink 52 is coated with graphene, it is possible to improve the heat dissipation properties of the heat sink 52 compared to an embodiment in which the heat sink 52 is not coated with graphene. Furthermore, according to Supplementary Note 1-1, since the heat sink 52 is coated with graphene, it is possible to reduce the possibility of corrosion of the main body portion 520 of the heat sink 52, and to prevent a decrease in the heat dissipation properties of the heat sink 52 due to corrosion of the heat sink 52, compared to an embodiment in which the heat sink 52 is not coated with graphene.

[0135] <<Appendix 1-2>> The inkjet printer 1 according to Supplementary Note 1-2 is the inkjet printer 1 according to Supplementary Note 1-1, characterized in that part of the ink ejected from the liquid ejection unit 3 is turned into mist.

[0136] According to Supplementary Note 1-2, since the heat sink 52 is coated with graphene, the possibility that the main body portion 520 of the heat sink 52 is corroded by the mist can be reduced compared to an embodiment in which the heat sink 52 is not coated with graphene.

[0137] <<Appendix 1-3>> The inkjet printer 1 according to Supplementary Note 1-3 is the inkjet printer 1 according to Supplementary Note 1-1 or Supplementary Note 1-2, characterized in that the main body portion 520 is coated with multi-layered graphene.

[0138] According to Supplementary Notes 1-3, since the heat sink 52 is coated with multiple layers of graphene, the possibility that the main body portion 520 of the heat sink 52 will be corroded by the mist can be reduced compared to an embodiment in which the heat sink 52 is not coated with a single layer of graphene.

[0139] <<Appendix 1-4>> The inkjet printer 1 according to Supplementary Note 1-4 is the inkjet printer 1 according to Supplementary Note 1-1 to Supplementary Note 1-3, characterized in that the main body 520 is composed of a base 5201 extending on a plane PL1 having a normal direction in the Z1 direction, a fin 5202 connected to a connection part PY1 of the base 5201 and extending on a plane PL2 having a normal direction in the Y1 direction that intersects the Z1 direction, and a fin 5203 connected to the connection part PY2 of the base 5201 and extending on a plane PL3 having a normal direction in the Y1 direction. In addition, in Supplementary Note 1, the Z1 direction is an example of a "first direction," and the Y1 direction is an example of a "second direction."

[0140] In Supplementary Note 1-4, the heat sink 52 has a simple shape having two fins, fin 5202 and fin 5203, and therefore the weight of the heat sink 52 can be reduced compared to the heat sink 52W having a large number of fins. Also, in Supplementary Note 1-4, the heat sink 52 is coated with graphene, and therefore high heat dissipation performance can be ensured in the heat sink 52. That is, according to Supplementary Note 1-4, it is possible to achieve both a reduction in the weight of the heat sink 52 and high heat dissipation performance in the heat sink 52.

[0141] <<Appendix 1-5>> The inkjet printer 1 according to Supplementary Note 1-5 is the inkjet printer 1 according to Supplementary Notes 1-1 to 1-4, and includes a liquid ejection unit 3 and a drive signal generation unit 5, and a carriage 110 that moves on a recording paper PP from which ink is ejected from the liquid ejection unit 3, and a carriage conveyance motor 91 for moving the carriage 110, and is characterized in that the liquid ejection unit 3 ejects ink when the carriage 110 is moving.

[0142] According to Supplementary Note 1-5, since the carriage 110 mounts the drive signal generation unit 5 having the heat sink 52, it is possible to reduce the load on the carriage conveyance motor 91 as compared with the aspect of mounting the drive signal generation unit 5W having the heat sink 52W.

[0143] <<E.2. Supplementary Note 2>> Hereinafter, the inkjet printer 1 according to Supplementary Note 2 will be described.

[0144] <<Supplementary Note 2-1>> The inkjet printer 1 according to Supplementary Note 2-1 includes a piezoelectric element PZ[m] driven by a drive signal Com, and a liquid ejection unit 3 that ejects ink in response to the drive of the piezoelectric element PZ[m], and a drive signal generation unit 5B that generates the drive signal Com. The drive signal generation unit 5B includes an integrated circuit 40 that generates a gate signal SG1 and a gate signal SG2, a transistor Tr1 to which the gate signal SG1 is input, a transistor Tr2 to which the gate signal SG2 is input, an inductor L0 having one end electrically connected to the transistor Tr1 and the transistor Tr2 and the other end electrically connected to an output terminal Tn-out that outputs the drive signal Com, a substrate 51 on which the integrated circuit 40, the transistor Tr1, the transistor Tr2, and the inductor L0 are mounted, and a molding member 55 that covers the transistor Tr1 on the substrate 5, and is characterized in that the transistor Tr1 has a Cu clip structure.

[0145] According to Supplementary Note 2-1, because the transistor Tr1 has a Cu clip structure, the transistor Tr1 can dissipate heat not only from the substrate 51 side but also from the side opposite the substrate 51. Therefore, according to Supplementary Note 2-1, compared to an embodiment in which the transistor Tr1 does not have a Cu clip structure, it is possible to improve the heat dissipation properties of the transistor Tr1 and prevent the transistor Tr1 from becoming too hot. Also, according to Supplementary Note 2-1, because the drive signal generation unit 5B includes a molding member 55 that covers the transistor Tr1, it is possible to reduce the possibility of the transistor Tr1 failing due to ink adhering to the transistor Tr1 compared to an embodiment in which the molding member 55 is not included.

[0146] <<Appendix 2-2>> The inkjet printer 1 according to Supplementary Note 2-2 is the inkjet printer 1 according to Supplementary Note 2-1, characterized in that the pH of the liquid ejected from the liquid ejection unit 3 is 3 or less.

[0147] According to Appendix 2-2, the drive signal generating unit 5B is provided with a molded member 55 that covers the transistor Tr1, so that the possibility of corrosion of the transistor Tr1 can be reduced even in a situation where a liquid with a pH of 3 or less is ejected from the liquid ejection unit 3 and metal corrosion is likely to occur within the inkjet printer 1.

[0148] <<Appendix 2-3>> The inkjet printer 1 according to Appendix 2-3 is the inkjet printer 1 according to Appendix 2-1 or Appendix 2-2, and is characterized in that it is equipped with a liquid ejection unit 3 and a drive signal generation unit 5B, and is equipped with a carriage 110 that moves over recording paper PP onto which ink is ejected from the liquid ejection unit 3, and a carriage transport motor 91 for moving the carriage 110, and the liquid ejection unit 3 ejects ink while the carriage 110 is moving.

[0149] According to Supplementary Note 2-3, because the transistor Tr1 has a Cu clip structure, the impact resistance of the drive signal generation unit 5B including the transistor Tr1 can be improved compared to an embodiment in which the transistor Tr1 is connected to the substrate 51 by a wire or the like. Therefore, according to Supplementary Note 2-3, even when the drive signal generation unit 5B including the transistor Tr1 is mounted on the carriage 110 and there is a high possibility that the drive signal generation unit 5B will be subjected to an impact, it is possible to achieve a long life for the drive signal generation unit 5B.

[0150] <<Appendix 2-4>> The inkjet printer 1 according to Supplementary Note 2-4 is the inkjet printer 1 according to Supplementary Note 2-1 to Supplementary Note 2-3, characterized in that the transistor Tr1 comprises a chip main body 60, a drain electrode 61d provided on a surface 601 of the multiple surfaces of the chip main body 60 that faces the substrate 51, and a source electrode 61s provided on a surface 602 of the multiple surfaces of the chip main body 60 opposite to surface 601, the drain electrode 61d being connected to a drain connection terminal 62d provided on the substrate 51, the source electrode 61s being connected to a conductive clip 63, and the clip 63 being connected to a source connection terminal 62s provided on the substrate 51. In addition, in Supplementary Note 2, surface 601 is an example of a "first surface," and surface 602 is an example of a "second surface."

[0151] According to Supplementary Note 2-4, the heat generated in the source electrode 61s and the drain electrode 61d of the transistor Tr1, which generate a large amount of heat, is dissipated from two surfaces, namely surfaces 601 and 602, of the chip main body 60, thereby improving the heat dissipation performance of the transistor Tr1 compared to a configuration in which heat is dissipated from a single surface of the chip main body 60.

[0152] <<Appendix 2-5>> The inkjet printer 1 according to Supplementary Note 2-5 is the inkjet printer 1 according to Supplementary Note 2-1 to Supplementary Note 2-3, characterized in that the transistor Tr1 comprises a chip main body 60, a source electrode 61s provided on a surface 601 of the multiple surfaces of the chip main body 60 that faces the substrate 51, and a drain electrode 61d provided on a surface 602 of the multiple surfaces of the chip main body 60 opposite to surface 601, the source electrode 61s being connected to a source connection terminal 62s provided on the substrate 51, the drain electrode 61d being connected to a conductive clip 63, and the clip 63 being connected to a drain connection terminal 62d provided on the substrate 51.

[0153] According to Appendix 2-5, the heat generated in the source electrode 61s and the drain electrode 61d of the transistor Tr1, which generate a large amount of heat, is dissipated from two surfaces, namely surfaces 601 and 602, of the chip main body 60, thereby improving the heat dissipation performance of the transistor Tr1 compared to a configuration in which heat is dissipated from a single surface of the chip main body 60.

[0154] <<Appendix 2-6>> The inkjet printer 1 according to Appendix 2-6 is the inkjet printer 1 according to Appendix 2-1 to Appendix 2-5, characterized in that the gate signal SG1 is a signal that specifies whether transistor Tr1 is on or off, and has a frequency of 1 MHz or more and 8 MHz or less.

[0155] According to Supplementary Note 2-6, it is possible to improve the accuracy of the waveform of the drive signal Com generated in the drive signal generating unit 5B including the transistor Tr1 and reduce the switching loss in the transistor Tr1 at the same time.

[0156] <<Appendix 2-7>> The inkjet printer 1 according to Supplementary Note 2-7 is the inkjet printer 1 according to Supplementary Note 2-1 to Supplementary Note 2-6, characterized in that the molding member 55 covers the transistor Tr1 and the transistor Tr2 on the substrate 51.

[0157] According to Supplementary Note 2-7, since the two transistors Tr, i.e., transistor Tr1 and transistor Tr2, are in one package, it is possible to reduce the component constants and the mounting area of transistor Tr1 and transistor Tr2 as compared with the aspect in which transistor Tr1 and transistor Tr2 are separate. Therefore, according to Supplementary Note 2-7, it is possible to miniaturize and lighten the drive signal generation unit 5B.

[0158] <<E.3. Supplementary Note 3>> Hereinafter, the inkjet printer 1 according to Supplementary Note 3 will be described.

[0159] <<Supplementary Note 3-1>> The inkjet printer 1 according to Supplementary Note 3-1 includes a piezoelectric element PZ[m] driven by a drive signal Com, and a liquid ejection unit 3 that ejects ink in response to the driving of the piezoelectric element PZ[m], and a drive signal generation unit 5C that generates the drive signal Com. The drive signal generation unit 5C includes an integrated circuit 40 that generates a gate signal SG1 and a gate signal SG2, a transistor Tr1 to which the gate signal SG1 is input, a transistor Tr2 to which the gate signal SG2 is input, an inductor L0 having one end electrically connected to the transistor Tr1 and the transistor Tr2 and the other end electrically connected to an output terminal Tn-out that outputs the drive signal Com, a substrate 51 on which the integrated circuit 40, the transistor Tr1, the transistor Tr2, and the inductor L0 are mounted, and a heat sink 56 provided on the opposite side of the substrate 51 as viewed from the transistor Tr1 and radiating heat from a surface 602 on the opposite side of the substrate 51 among the plurality of surfaces of the chip main body portion 60 of the transistor Tr1. In Supplementary Note 3, the surface 602 is an example of the "first surface", and the heat sink 56 is an example of the "first heat sink".

[0160] According to Supplementary Note 3-1, the drive signal generating unit 5C has the heat sink 56, and therefore the transistor Tr1 can dissipate heat not only from the side of the substrate 51 but also from the side opposite the substrate 51. Therefore, according to Supplementary Note 3-1, compared to an embodiment in which the drive signal generating unit 5C does not have the heat sink 56, it is possible to improve the heat dissipation properties of the transistor Tr1 and prevent the transistor Tr1 from becoming too hot.

[0161] <<Appendix 3-2>> The inkjet printer 1 according to Appendix 3-2 is the inkjet printer 1 according to Appendix 3-1, characterized in that it comprises a molding member 55 that covers the transistor Tr1 on the substrate 51, and the pH of the liquid ejected from the liquid ejection unit 3 is 3 or less.

[0162] According to Appendix 3-2, the drive signal generating unit 5C is provided with a molded member 55 that covers the transistor Tr1, so that the possibility of corrosion of the transistor Tr1 can be reduced even in a situation where a liquid with a pH of 3 or less is ejected from the liquid ejection unit 3 and metal corrosion is likely to occur within the inkjet printer 1.

[0163] <<Appendix 3-3>> The inkjet printer 1 according to Appendix 3-3 is the inkjet printer 1 according to Appendix 3-1 or Appendix 3-2, and is characterized in that it is equipped with a liquid ejection unit 3 and a drive signal generation unit 5C, and is equipped with a carriage 110 that moves over recording paper PP onto which ink is ejected from the liquid ejection unit 3, and a carriage transport motor 91 for moving the carriage 110, and the liquid ejection unit 3 ejects ink while the carriage 110 is moving.

[0164] According to Appendix 3-3, since the drive signal generating unit 5C is mounted on the carriage 110 and moves, heat can be dissipated more efficiently from the heat sink 56 than in a configuration in which the drive signal generating unit 5C is not mounted on the carriage 110.

[0165] <<Appendix 3-4>> The inkjet printer 1 according to Supplementary Note 3-4 is the inkjet printer 1 according to Supplementary Note 3-1 to Supplementary Note 3-3, characterized in that the transistor Tr1 has a Cu clip structure.

[0166] According to Supplementary Note 3-4, compared to an embodiment in which the transistor Tr1 does not have a Cu clip structure, it is possible to improve the heat dissipation properties of the transistor Tr1, and it is possible to prevent the transistor Tr1 from becoming too hot.

[0167] <<Appendix 3-5>> The inkjet printer 1 according to Supplementary Note 3-5 is the inkjet printer 1 according to Supplementary Note 3-1 to Supplementary Note 3-4, characterized in that the transistor Tr1 includes a chip body 60, a source electrode 61s provided on a surface 602 of the multiple surfaces of the chip body 60, and a drain electrode 61d provided on a surface 601 of the multiple surfaces of the chip body 60 opposite to surface 602, the drain electrode 61d being connected to a drain connection terminal 62d provided on the substrate 51, the source electrode 61s being connected to a conductive clip 63, and the clip 63 being connected to a source connection terminal 62s provided on the substrate 51. In addition, in Supplementary Note 3, surface 601 is an example of a "second surface."

[0168] According to Supplementary Note 3-5, the heat generated in the source electrode 61s and the drain electrode 61d of the transistor Tr1, which generate a large amount of heat, is dissipated from two surfaces, namely surfaces 601 and 602, of the chip main body 60, thereby improving the heat dissipation performance of the transistor Tr1 compared to a configuration in which heat is dissipated from a single surface of the chip main body 60.

[0169] <<Appendix 3-6>> The inkjet printer 1 according to Appendix 3-6 is the inkjet printer 1 according to Appendix 3-1 to Appendix 3-5, characterized in that the transistor Tr1 comprises a chip main body 60, a drain electrode 61d provided on surface 602 of the multiple surfaces of the chip main body 60, and a source electrode 61s provided on surface 601 opposite surface 602 of the multiple surfaces of the chip main body 60, the source electrode 61s being connected to a source connection terminal 62s provided on the substrate 51, the drain electrode 61d being connected to a conductive clip 63, and the clip 63 being connected to the drain connection terminal 62d provided on the substrate 51.

[0170] According to Supplementary Note 3-6, the heat generated in the source electrode 61s and the drain electrode 61d of the transistor Tr1, which generate a large amount of heat, is dissipated from two surfaces, namely surfaces 601 and 602, of the chip main body 60, thereby improving the heat dissipation performance of the transistor Tr1 compared to a configuration in which heat is dissipated from a single surface of the chip main body 60.

[0171] <<Appendix 3-7>> The inkjet printer 1 according to Supplementary Note 3-7 is the inkjet printer 1 according to Supplementary Note 3-1 to Supplementary Note 3-6, characterized in that the heat sink 56 has a main body portion 560 formed from copper or aluminum, and the main body portion 560 is coated with graphene.

[0172] According to Supplementary Note 3-7, since the heat sink 56 is coated with graphene, it is possible to improve the heat dissipation performance of the heat sink 56 compared to an embodiment in which the heat sink 56 is not coated with graphene. Furthermore, according to Supplementary Note 3-7, since the heat sink 56 is coated with graphene, it is possible to reduce the possibility of corrosion of the main body portion 560 of the heat sink 56, and to prevent a decrease in the heat dissipation performance of the heat sink 56 due to corrosion of the heat sink 56, compared to an embodiment in which the heat sink 56 is not coated with graphene.

[0173] <<Appendix 3-8>> The inkjet printer 1 according to Appendix 3-8 is the inkjet printer 1 according to Appendix 3-1 to Appendix 3-7, characterized in that the gate signal SG1 is a signal that specifies whether transistor Tr1 is on or off, and has a frequency of 1 MHz or more and 8 MHz or less.

[0174] According to Supplementary Note 3-8, it is possible to improve the accuracy of the waveform of the drive signal Com generated in the drive signal generating unit 5C including the transistor Tr1 and reduce the switching loss in the transistor Tr1 at the same time.

[0175] <<Appendix 3-9>> The inkjet printer 1 according to Supplementary Note 3-9 is the inkjet printer 1 according to Supplementary Note 3-1 to Supplementary Note 3-8, characterized in that it includes a molding member 55 on the substrate 51 that covers the transistor Tr1 and the transistor Tr2.

[0176] According to Supplementary Note 3-9, two transistors Tr, transistor Tr1 and transistor Tr2, are packaged together in one package, which makes it possible to reduce the component constants and the mounting area of ​​transistor Tr1 and transistor Tr2 compared to an embodiment in which transistor Tr1 and transistor Tr2 are separate.

[0177] <<Appendix 3-10>> The inkjet printer 1 according to Supplementary Note 3-10 is the inkjet printer 1 according to Supplementary Note 3-1 to Supplementary Note 3-9, characterized in that it includes a heat sink 52 fixed to the substrate 51. In addition, in Supplementary Note 3, the heat sink 52 is an example of a "second heat sink."

[0178] According to Supplementary Note 3-10, heat dissipation is possible through the heat sink 56 and through the heat sink 52, so that the heat dissipation efficiency in the drive signal generating unit 5C can be improved compared to an embodiment that does not include the heat sink 52. [Explanation of symbols]

[0179] 1...inkjet printer, 2...control unit, 3...liquid ejection unit, 4...drive signal generation circuit, 5...drive signal generation unit, 9...transport unit, 31...supply circuit, 32...liquid ejection head, 40...integrated circuit, 41...amplification circuit, 42...smoothing circuit, 43...pull-up circuit, 44...filter circuit, 51...substrate, 52...heat sink, 55...molding member, 56...heat sink, 60...chip main body, 61d...drain electrode, 61g...gate electrode, 61s...source electrode, 62d...drain connection terminal, 62g...gate connection terminal, 62s...source connection terminal, 63...clip, 64...wire, 91...carriage transport motor, 92...medium transport motor, 93...medium transport mechanism, 110...carriage, 520...main body portion, 521...coating portion, D...ejection portion, L0...inductor, Tr1...transistor, Tr2...transistor.

Claims

1. a liquid ejection unit including a drive element driven by a drive signal, and ejecting liquid in response to the drive of the drive element; a drive signal generating unit for generating the drive signal; Equipped with The drive signal generating unit an integrated circuit that outputs a first control signal and a second control signal; a first transistor to which the first control signal is input; a second transistor to which the second control signal is input; a coil having one end electrically connected to the first transistor and the second transistor and the other end electrically connected to an output terminal that outputs the drive signal; a substrate on which the integrated circuit, the first transistor, the second transistor, and the coil are mounted; a molding member that covers the first transistor on the substrate; Equipped with the first transistor has a Cu clip structure; A liquid ejection device characterized by:

2. the pH of the liquid discharged from the liquid discharge unit is 3 or less; The liquid ejection device according to claim 1 .

3. a carriage that carries the liquid ejection unit and the drive signal generation unit and moves over a medium onto which liquid is ejected from the liquid ejection unit; a motor for moving the carriage; Equipped with the liquid ejection unit ejects liquid while the carriage is moving; The liquid ejection device according to claim 1 .

4. The first transistor is a chip body; a drain electrode provided on a first surface of the chip body that faces the substrate; a source electrode provided on a second surface of the chip body opposite to the first surface; Equipped with the drain electrode is connected to a drain connection terminal provided on the substrate, the source electrode is connected to a conductive clip; The clip is connected to a source connection terminal provided on the substrate. The liquid ejection device according to claim 1 .

5. The first transistor is a chip body; a source electrode provided on a first surface of the chip body that faces the substrate; a drain electrode provided on a second surface of the chip body opposite to the first surface; Equipped with the source electrode is connected to a source connection terminal provided on the substrate; the drain electrode is connected to a conductive clip; The clip is connected to a drain connection terminal provided on the substrate. The liquid ejection device according to claim 1 .

6. the first control signal is a signal that specifies whether the first transistor is turned on or off, and has a frequency of 1 MHz or more and 8 MHz or less; The liquid ejection device according to claim 1 .

7. the molding member covers the first transistor and the second transistor on the substrate; The liquid ejection device according to claim 1 .

8. A liquid ejection unit including a drive element driven by a drive signal, which ejects liquid in response to the driving of the drive element, an integrated circuit that outputs a first control signal and a second control signal; a first transistor to which the first control signal is input; a second transistor to which the second control signal is input; a coil having one end electrically connected to the first transistor and the second transistor and the other end electrically connected to an output terminal that outputs the drive signal; a substrate on which the integrated circuit, the first transistor, the second transistor, and the coil are mounted; a molding member that covers the first transistor on the substrate; Equipped with the first transistor has a Cu clip structure; A liquid ejection unit characterized by:

9. the pH of the liquid discharged from the liquid discharge unit is 3 or less; The liquid discharge unit according to claim 8 .

10. The liquid ejection unit includes: the liquid ejection unit is mounted on a carriage that moves over a medium onto which the liquid is ejected; The liquid is ejected while the carriage is being moved by a motor for moving the carriage. The liquid discharge unit according to claim 8 .

11. The first transistor is a chip body; a drain electrode provided on a first surface of the chip body that faces the substrate; a source electrode provided on a second surface of the chip body opposite to the first surface; Equipped with the drain electrode is connected to a drain connection terminal provided on the substrate, the source electrode is connected to a conductive clip; The clip is connected to a source connection terminal provided on the substrate. The liquid discharge unit according to claim 8 .

12. The first transistor is a chip body; a source electrode provided on a first surface of the chip body that faces the substrate; a drain electrode provided on a second surface of the chip body opposite to the first surface; Equipped with the source electrode is connected to a source connection terminal provided on the substrate; the drain electrode is connected to a conductive clip; The clip is connected to a drain connection terminal provided on the substrate. The liquid discharge unit according to claim 8 .

13. the first control signal is a signal that specifies whether the first transistor is turned on or off, and has a frequency of 1 MHz or more and 8 MHz or less; The liquid discharge unit according to claim 8 .

14. the molding member covers the first transistor and the second transistor on the substrate; The liquid discharge unit according to claim 8 .

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